Circuit breaker panel boards, load centers and the like are normally enclosed within box-like structures. Many of these enclosures are metallic being mass produced from metal sheets in a succession of operations, including cutting, blanking, forming and welding to create a box like housing which must then be painted. The enclosure covers are similarly produced in a succession of operations. A number of components, including components mounted in and supporting elements, must then be assembled in a box-like housing. Since the metallic enclosure is electrically conductive, insulation must be incorporated into the mounting of bus bars and other components in the housing.
U.S. Pat. No. 3,852,514 to Lauben discloses a non-metallic, molded plastic electrical equipment enclosure for electrical equipment, such as a panel board or load center for circuit breakers having integrally formed back and side walls in the configuration of a box-like housing. A separate moldable plastic cover is placed on the housing to complete the enclosure. Lauben prefers to provide housing sidewalls which terminate in a parametrical lip circumscribing the open front of the housing. The lip telescopically interfits with a corresponding parametrical flange molded to and depending from the front wall of the cover. The cover can further be secured by tabs or screws. Lauben also teaches that the housing and the cover are formed of a suitable plastic, preferably a thermoplastic material such as phenylene-oxide thermoplastic and that thermoset materials may also be used.
In many installations it is important that the cover be securely attached to the housing so that it cannot be readily removed. In many applications a door is provided in the cover which can be locked through the use of a padlock placed in a lock tab passing from the cover through the door. If the cover or the door has been secured by exposed screws or hinges, the enclosure is easily entered by removing the screws or hinges. For many installations this is undesirable.
Many enclosures for electrical equipment are placed outside where they are exposed to rain, wind and snow. For such uses it is important that the enclosure be water-tight. To accomplish this purpose the art has provided seals on mating surfaces of the cover and housing or applied sealants to the enclosure. These practices increase the cost of the enclosure. There is, therefore, a need for a tamper proof molded enclosure for electrical components which is weather proof.